Polycarbonate resins are a resin excellent in a heat-resistance, a mechanical property and an electric characteristic, and is used generally, for example, for automobile materials, electric and electronic device materials, residential materials and materials for producing parts in other industrial fields, etc. In particular, a flame-retardant polycarbonate resin composition is favorably used as members of OA/information devices such as computers, notebooks, cellular phones, printers, and copying machines.
As a means for giving a flame resistance to a polycarbonate resin, conventionally, a halogen-based flame retardant or a phosphorous-based flame retardant has been blended to a polycarbonate resin. However, a polycarbonate resin composition blended with a halogen-based flame retardant containing chlorine or bromine occasionally causes the deterioration of thermal stability or the corrosion of a screw or a mold of a molding machine in molding. Moreover, a polycarbonate resin composition blended with a phosphorous-based flame retardant hinders it high transparency, which is a feature of polycarbonate resin, or deteriorates the impact resistance and the heat-resistance, to sometimes limit the application of the composition. In addition, since these halogen-based flame retardants and phosphorous-based flame retardants may bring about environmental pollution when the product is scrapped or recovered. Therefore, it is desired that a flame resistance is imparted without using these flame retardants.
Under such circumstances, in these years, metal organic sulfonate compounds represented by alkali metal organic sulfonate compounds and alkali earth metal organic sulfonate compounds (for example, see Patent Documents 1 to 2) are actively examined as a useful flame retardant.
However, the flame resistance achieved by blending a metal organic sulfonate alone into a polycarbonate resin is limited, and can not attain such high flame-resistant level as required in these years. For the metal organic sulfonate, the flame resistance to a polycarbonate resin is imparted through a catalytic function. When it is added in a large amount so as to obtain a high flame resistance, the flame resistance is not enhanced, but, inversely, is deteriorated.
On the other hand, the technique of blending a polyalkylsilsesquioxane particle to a polycarbonate resin is publicly known (see Patent Documents 3 to 4). In such a case, the purpose of blending the polyalkylsilsesquioxane particle is to give a diffusible property to the polycarbonate resin.
Moreover, a technique of blending the metal organic sulfonate and the silsesquioxane to a polycarbonate resin is proposed to improve the flame resistance (see Patent Documents 5 to 6).
It is described that, on this occasion, the use of a silsesquioxane having a particular functional group such as an epoxy group, a vinyl group or a phenyl group is necessary in order to improve the flame resistance.
However, in actual, it is difficult to obtain such a silsesquioxane industrially, and the level of the flame resistance is insufficient.
Furthermore, Patent Documents 7 to 8 describe a polycarbonate resin composition formed by blending a polyalkylsilsesquioxane, a metal organic sulfonate and a fluoropolymer to a polycarbonate resin. However, the level of a flame resistance is still insufficient, and, specifically, it can not attain a flame resistance of V-1 or higher according to the UL94 standard in a thickness of 0.8 mm or less.
Moreover, the composition is difficult to exert a impact resistance required for materials of a body of equipment etc., and there is such a problem that a impact resistance deteriorates significantly, in particular, when molding is carried out at a high temperature along with the size increase, or thickness reduction and size reduction of parts, when the product shape is made complex so as to have various corner R portions for enhancing the latitude of product design and attaining the size reduction, and when heat is applied for a long time.